If you are America’s largest online retailer, you don’t have to offer coupons or cash back deals to get people to buy from your web store. But if you are an Amazon customer, there are still ways to maximize the savings you get when making purchases on Amazon.com.

First, there’s Amazon Prime, which, for $79 offers 2-day shipping for an entire year on “millions of items” sold on Amazon, and, in my experience, almost all items shipped by Amazon itself. Students can get one year of Amazon Prime for free, and pay only $39 per year subsequently. If you shop a lot online, or are in the market for some bulky item with a high shipping charge, Amazon Prime may be a good deal.

But to get the most out of your Amazon purchases, look into double-dipping. Since August 2011, Hawaiian Airlines’ eMarket has been giving miles, now downgraded to 1 mile per dollar, for purchases made on Amazon.com. US Airways briefly also offered this deal, but has since pulled it down, making the eMarket currently the only portal worth a visit before an Amazon purchase.

earn miles on Amazon purchases through Hawaiian Airlines’ eMarket portal

To double-dip, take a peek in your wallet. This quarter, from January 1st to March 31st, 2012, Chase Freedom cardholders get 5% cash back on up to $1500 spent on gas and Amazon.com. Unless you spend over $100 on gas every week, the $1500 ceiling should be enough to let you effectively get up to 5% in savings when shopping on Amazon until the end of March.

If you don’t have the Chase Freedom card, the Citi Forward card may do the trick as well. Currently, the Citi Forward card, which gives 5 points per dollar on restaurants, books, music, and movies, seems to categorize purchases made on Amazon.com as “books,” effectively yielding 5% cash back when buying through the online retailer. However, unlike Chase Freedom’s deal, which explicitly includes Amazon.com in its 5% cash back category, Citi Forward does not offer a list of retailers eligible for earning 5 points per dollar. In other words, it’s a very sweet deal right now, but you should keep an eye on your statements since Citi can decide at any time that what you’re buying on Amazon doesn’t really count as a book.

On the other hand, if you’re looking to use points and save on cash when buying on Amazon, check your Discoverbalance instead. In October 2011, Discover announced a new redemption option for its cash back program: spend it on Amazon. The dollars are spent 1-to-1, but while statement credits and direct deposits can only be redeemed in increments of $50, the “pay with Cashback Bonus” option for Amazon allows Discover cardholders to redeem any amount of cash back on an Amazon purchase, which means you don’t have to wait as long to transform the cash back you earned into real cash. For this, all you have to do is link your Discover and Amazon accounts here.

But whether you use the Chase Freedom or Citi Forward card to earn more points, or Discover to redeem points, don’t forget to go through Hawaiian’s eMarket. Even though Amazon’s prices are often already a good deal, and there aren’t many coupons to be found, double-dipping can still maximize what you get out of your Amazon.com purchase.

To save when shopping online it is well established that you should (1) run a quick search for coupons and (2) shop through an online portal if you can. But until recently, if you were buying anything on Amazon, there was no way to double-dip. You could of course get points/miles through your credit card, but there wasn’t any portal offering points/miles or cash back for Amazon purchases. This changed very recently: now, US Airways’ Shopping Mall now gives 1 mile per $1 spent on amazon.com and Hawaiian Airlines’ eMarket gives 2 miles per $1 spent!

If you are a member of any of these two airline programs and make a lot of purchases on Amazon, this is amazing news. All you have to do is register at the respective portal, and remember to reach Amazon by clicking through the portal link rather than typing it on your browser bar directly when making a purchase.

Amazon.com now on Hawaiian's eMarket

If you shop on Amazon frequently but are not a member of US Airways’ Dividend Miles or Hawaiian’s HawaiianMiles frequent flier programs, there may still be something in it for you. Depending on how much you shop, it may be worthwhile to set up an account with either of the two programs and start accumulating miles anyway. A purchase here and there may not seem to make a difference, but given that membership is free and, for both programs, miles do not expire as long as you have an activity in the account every 18 months, if you buy stuff on Amazon there’s really no reason not to set up an account. In the worst case scenario, your miles expire and you earn nothing – and lose nothing. In the best case scenario, you either shop frequently enough to keep the account going and accumulate miles for a ticket eventually or, even better, you learn that you spend more on Amazon than you anticipated and earn a free ticket in no time.

When deciding for which of the two programs to sign up, there are some things to consider. On one hand, US Airways is a larger airline with more partners, so if you are looking for a mileage program in general, it’s a good bet. Once you’ve set up the account, you can always credit flights you take on US Airways as well as on other Star Alliance members, including United/Continental and international carriers such as Thai and Lufthansa, and accumulate miles even faster.

On the other hand, while Hawaiian is not in an alliance and only has 4 airline partners (Delta, Island Air, Korean Air, and Virgin Atlantic), its portal offers twice as many miles per dollar spent on Amazon. So, if you don’t fly on any of US Airways’ or Hawaiian’s partners, or already have your favorite frequent flier program, Hawaiian may be a good option just for earning those Amazon miles. Also, as has been pointed out by some very savvy people who know the ins-and-outs of frequent flier programs, every 5000 HawaiianMiles can be converted into 10,000 Hilton HHonors points, making this a compelling deal for Hilton HHonors members too.

Amazon’s new participation in US Airways’ Shopping Mall and Hawaiian’s eMarket portals is exciting news in general. For members of HawaiianMiles, US Airways’ Dividend Miles, or Hilton HHonors benefits could be great. But even if you aren’t a member of any of these programs, if you shop a lot on Amazon, there are probably still gains to be had by going through one of the two portals. And if you’re still not convinced, you could also sit back and wait: maybe Amazon’s participation in these two portals is a sign of even better times to come, when Amazon is giving miles, points, or cash back on every shopping portal out there.